Blow-out door for overpressure protection



Filed Oct. 18, 1962 May 11, 1965 A. L. STOCK 3,182,855

BLOW-OUT DOOR FOR OVERPRESSURE PROTECTION 2 Sheets-Sheet l INVENTORAlvin L. Stock May 11, 1965 A. STOCK 3,132,355

BLOW-OUT DOOR FOR QVERPRESSURE PROTECTION Filed Oct. 18, 1962 2Sheets-Sheet 2 United States Patent 3,182,855 BLOW-OUT DOOR FOROVERPRESSURE PROTECTION Alvin L. Stock, Drexel Hill, Pa., assignortoWestinghouse Electric Corporation, Pittsburgh, Pa, a corporation ofPennsylvania Filed Oct. 18, 1962, Ser. No. 231,474 6 Claims. (Cl.220-89) This invention rel-ates to apparatus for providing protectionagainst overpressure in fluid containing shell structure, and, moreparticularly, to an explosive or blow-out door structure for quicklyrelieving a fluid overpressure condition in such shell structure.

Heretofore, blow-out door structures have employed discs of either afrangible or shearable nature arranged to provide a fluid-tight seal butadapted to rupture at a predetermined pressure. Although blow-out doorstructures of this type have proven to be highly satisfactory anddependable, they are costly to manufacture, relatively heavy in weightdue to the number and arrangement of the components, and expensive toreseal in the field after rupture of the disc since the ruptured disc isnot reusable.

In view of the above, it is a primary object of the invention to providea blow-out door structure that obviates the rupturable disc.

It is a further object to provide a blow-out door structure that is lessexpensive to manufacture, lighter in weight and in which all of themanufactured components may be reused as often as desired.

Briefly, in accordance with the invention, there is provided a blow-outdoor structure including a body structure having an enlarged opening anda door member overlying and blocking the opening. The body structure andthe door member have mating surface portions encompassing the openinggnd bonded to each other by a layer of adhesive material, therebyfastening the door member to the body structure and providing apressure-tight seal preventing leakage of fluid therethrough in normaloperation. By properly proportioning the door, the mating surfaces andthe area of the adhesive material layer, the adhesive material layer iseffective to yield at a substantially predetermined overpressure value,thereby explosively releasing the door and permitting fluid to quicklyescape through the opening to the atmosphere before a dangerousoverpressure condition is attained.

. Although not limited thereto, the above blow-out door structure 'maybe advantageously employed to provide overpressureprotection on lowpressure steam turbines by mounting on the shell structure in registrywith a suitable opening. In such an environment, the temperaturesencountered may attain values of about 500 F. and the overpressurevalues are on the order of about to p.s.i.g. Adhesive materials found tobe suitable for such application are epoxy resins and silicone cements.

The foregoing and other objects are effected by the invention as will beapparent from the following description and claims taken in conjunctionwith the accompanying drawings, forming a part of this application, inwhich:

FIGURE 1 is an axial sectional view of a blow-out door structure formedin accordance with the invention;

FIG. 2 is a plan of the blow-out door structure shown in FIG. 1 with aportion cut away;

FIG. 3 is an axial sectional view showing a second embodiment of theinvention; and

FIG. 4 is a side elevational view of the structure shown in FIG. 3 witha portion cut away.

Referring to the drawings in detail, in FIGS. 1 and 2 there is shown anexplosion or blow-out door structure 5, formed in accordance with theinvention, including a body structure 10 of generally tubularconfiguration and having a generally cylindrical side wall 11 and acircumferential end portion 12. The end portion 12 is provided with aradially inwardly extending flange portion 13 forming an annularrecessed surface portion 14 and defining an enlarged central opening 15.There is further provided an imperforate door-member 16 of circular ordisc-like configuration having a circumferential flange portion 17providing an annular surface portion 18.

The door member 16 is of slightly smaller radial dimensionthan theflange 13 and is freely received therein with the surface portions 18and 14 disposed in mating face-to-face relation with each other, therebypositioning the door in the flange 13 for support thereby and preventingmovement of the door member 16 downwardly when viewed as shown inFIG. 1. Accordingly, when the door member 16 is positioned on the flange13, as shown, the opening 15 is blocked thereby.

The door member 16 is bonded to the flange 13 by a continuous layer ofadhesive material 20 interposed between the mating surfaces 14 and 18and substantially coextensive therewith, thereby forming apressure-tight seal to prevent leakage of fluid therepast.

The body structure is formed with its cylindrical wall portion 11 ofsubstantial axial extent to form a chamber 21. The chamber 21 is coveredat the upper end of the cylindrical wall 11 by an open framework guardor grid member 22 of any suitable type having a plurality of apertures23 formed therein to permit fluid to escape freely past the grid member22. The grid member 22 is attached to the wall portion 11 by anysuitable fastening means, for example, an annular array of screws 24.

The blow-out door structure 5 may be welded or otherwise attached to ashell structure 25 (shown in fragmentary form) of a fluid containingdevice to be protected against overpressure, for example, a low pressuresteam turbine unit, and is disposed in registry with a suitable aperture26. As well known, low pressure steam turbines are operable atrelatively low or even subatmospheric steam pressure values which may,from time-totime and for various reasons, exceed their maximum fluidpressure rating. Accordingly, for economic reasons such shells may bemade to withstand relatively low pressures on the order of from 5 to 10p.s.i.g., and protected against overpressure by the blow-out doorstructure.

Such shell structures further may contain steam at temperatures up toabout 500 F. When the blow-out door structure is employed foroverpressure protection in such an environment, the selection of theadhesive material must take into account the deteriorating effect oflong exposure to such temperature on the adhesive material. Epoxy resinsand silicone cements have been found highly suitable for suchapplications, since both of these adhesives are readily available, havethe special characteristic of being readily bondable to metals and donot appreciably age, maintaining their optimum properties attemperatures of up to at least 500 F. in a steam atmosphere. Theseadhesives, further maintain a high quality vacuum seal, While theirshear and tensile stress values are adequate and may be easily andconcisely determined in designing the blow-out door structure to yieldat a predetermined overpressure value.

In operation, the blow-out door structure prevents leakage of steam fromthe shell 25 during normal operation. However, should the internalpressure within the shell member exceed a predetermined safe value, thelayer of adhesive material 20 will commence to yield, thereby permittingthe door member 16 to move outwardly and relieve the internal pressure.As the door member 16 moves outwardly, under the influence of the steam,it has imparted thereto a relatively high degree of kinetic energy.However, this kinetic energy is absorbed by the guard member 22 whichalso serves to hold the door member 16 captive within the chamber 21,while permitting the excessive steam to flow freely through the centralopening 15 and the chamber 21 to the atmosphere.

The cylindrical wall portion 11 serves to direct the flow of escapingsteam in any desired direction, for example, ,in a direction away fromoperating personnel or apparatus that may otherwise be harmed by thesteam. Accordingly, the blow-out door structure may be connected to theshell structure 25 in any suitable position or attitude, as desired.

To restore the blow-out door structure to its original operative andsealing status after a blow-out has been incurred, the guard member 22is first removed by removing the screws 24, thereby rendering the doormember 16 readily accessible. The door member 16 is then removed and theannular surface 18 thereon, as well as the flange surface 14, isprepared for a new layer of adhesive material by removing therefrom theold adhesive material. This may be accomplished by a knife or othersuitable scraping device. After a new layer of adhesive material isapplied to the mating surfaces 14 and 18 and the door member 16 isreplaced, the guard member 22 is repositioned and attached by the screws24. After a suitable length of time to permit the epoxy resin or thesilicone cement to become fixed or cured, the blow-out door structure isready to be put into service again.

By suitably proportioning the door member 16, the

opening and the mating surfaces 14 and 18, the blowout door structuremay be made effective to safely vent fluid from the shell 23 at anypredetermined over-pressure value. This may be more readily understoodby considering that the layer of adhesive material has a substantiallyuniform tensile strength per unit of surface area. Hence, by increasingthe surface area of the adhesive layer, the force that the layer willwithstand is proportionately higher. Conversely, by reducing the area ofthe adhesive layer, the force that it will withstand is proportionatelyreduced. The invention is susceptible of many embodiments, andmodifications, and, as illustrated in FIGS. 3 and 4, there is shown asecond embodiment of a blow-out door structure 35, similar to theblow-out door structure shown in FIGS. 1 and 2. This embodiment may beemployed with a vertically extending shell portion 36 of a steam turbineor the like and includes an annular mounting member 37 defining anenlarged opening 38. The mounting member 37 may be connected to theshell portion 36 in any suitable manner, such as by welding, asindicated at 39. A body structure 40 is clamped on the mounting memberby an annual array of suitable bolts 41 received in suitable aperturesprovided in a radially outwardly extending flange portion 42. The flangeportion 42 is of circular configuration and encompasses an enlargedcentral opening 43'disposed in registry with the opening 38. The bodystructure 40 further includes an upstanding wall portion 44 of arcuatecross-section (FIG. 4) to which is attached a generally circulardeflector plate 45. The deflector plate 45 is attached to the wallportion 44 by an annular array of screws 46.

The wall portion 44, the flange portion 42 and the deflector plate 45define an outlet opening 49 providing a fluid communication between theatmosphere and the opening 43. A plurality of spaced rods 50 extendacross the opening 49 and are connected at opposite ends to the flange42 and to the deflector plate 45, thereby forming an open frameworkdividing the outlet 49 into a plurality of openings of smaller extent insubstantially the same manner as the grid member 22 described inconjunction with the first embodiment. The body 40 is, in the samemanner as described in conjunction with the first embodiment, providedwith a radially inwardly extending circumferential flange portion 52having an annular surface portion 53 encompassing the opening 43 anddisposed in face-to-face relation with a mating annular surface portion54 provided on a circular door member 55. Between the mating surfaces 53and 54 there is provided a layer of suitable adhesive material 56bonding the door member to the flange portion 51. This material may beselected as desired to suit its particular environment, as mentionedpreviously.

Since the body portion 48 is detachably connected to the mounting member37 by the screws 41, a suitable sealing gasket 57 may be employed toprovide a leakproof seal therebetween. This gasket 57 may be formed ofany suitable material, for example, silicone sponge rubber. v

The blow-out door structure 35 operates in substantially the same manneras the blow-out door structure 5 described in connection with the firstembodiment. That is, when the internal steam pressure within the shell36 exceeds a predetermined safe value, the layer of adhesive materialyields and permits the door member 55 to move outwardly, thereby ventingthe interior of the shell 36 to the atmosphere through the opening 43.

As the door member 55 moves explosively outwardly by the steam flowingtherepast, its motion is arrested by the deflector member 45 and itskinetic energy safely dissipated. The escaping steam is directedoutwardly through the opening 49 in a direction generally transverse tothe axis of the opening 43 so that the flow path of the steam after itis ejected to the atmosphere is generally parallel to the surface of theshell 36 and directed upwardly as viewed in FIG. 3.

After an explosion, the blow-out door structure may be serviced insubstantially the same manner as described in connection with the firstembodiment and restored to service in the field.

With this arrangement, the blow-out door structure 35 may also beemployed as an access door, permitting access to the interior of theshell 36 for inspection or servicing purposes, since to remove the doorstructure 35, it is only necessary to remove the mounting bolts 41.Hence, a separate access door (usually provided in apparatus of thistype) is not required.

It will now be seen that with both of the embodiments described inconnection with the invention, the door members 16 (FIGS. 1 and 2) and55 (FIGS 3 and 4) are not impaired or damaged in any way and may be usedrepeatedly. Hence, the only material required to restore the blow-outdoor structure to the original factory obtained sealing condition is asupply of the sealing material desired.

It will now be further seen that the invention provides a readilyserviceable blow-out door structure that includes a minimum of essentialcomponents and that these components may be made of relatively lightmaterial, no heavier than required to withstand the pressures requiredin service.

While the invention has been shown in several forms, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various changes and modifications without departing fromthe spirit thereof.

I claim as my invention:

1. A blow-out door structure for protecting a shell structure againstdamage due to internal overpressure, comprising a body structure havingan enlarged opening defined by a flange portion,

said flange portion having a substantially continuous first peripheralface portion,

a door member having a second peripheral face portion disposed inface-to-face relation with said first face portion,

a layer of adhesive material disposed between said first and second faceportions and coextensive peripherally therewith,

said layer of material bonding said door member to said body structureand providing a fluid-tight seal therebetween at total internalpressures below a predetermined value, but being yieldable atsubstantially said predetermined value to break said seal and re leasesaid door, and

means for holding said door captive in said body structure.

2. The structure recited in claim 1 in which said door holding meansincludes an open framework structure,

said framework structure being connected to said body structure andpermitting the door to move freely within the body structure.

3. A blow-out door structure for protecting a shell structure againstdamage due to internal overpressure, comprising a body structure havinga first planar surface portion,

said body portion having an enlarged opening encompassed by said surfaceportion,

a door member blocking said opening and having a second planar surfaceportion disposed in face-to-face relation with said first surfaceportion,

a layer of adhesive material disposed between said first and secondsurface portions and bonding said door member to said body structure,

said layer of material providing a fluid-tight seal between said doormember and said body at total internal pressures below a predeterminedvalue, but being yieldable at substantially said predetermined value tobreak said seal and permit said door to unblock said opening, and

means for holding said door captive in said body structure after saidopening is unblocked.

4. A blow-out door structure for explosively releasing internal fluidoverpressure in a shell structure, comprismg an annular mountingstructure defining an enlarged first central opening,

a body structure connected to said mounting structure,

said body structure having a second central opening disposed in registrywith said first opening,

said body structure having a first annular surface portion encompassingsaid second opening,

an imperforate door member blocking said second opening and having asecond surface portion disposed in face-to-face relation with said firstsurface portion,

an annular layer of adhesive material disposed between said first andsecond surface portions and bonding said door member to said bodystructure,

said layer of material providing a fluid-tight seal between said surfaceportions at total internal fluid pressures below a predetermined value,but being yieldable at total internal fluid pressures above said 5predetermined value to rupture said seal and permit said door toexplosively unblock said second open- 111g,

said body structure further including an open framework,

a wall portion disposed in spaced relation with said door and at leastpartly defining a third opening for directing the fluid to theatmosphere, and

an open framework extending across said third opensaid wall portionbeing further effective to arrest the movement and dissipate the kineticenergy of said door during an explosion.

5. The structure recited in claim 4 in which said body structure isdetachably connected to said mounting structure by an annular array ofbolts, whereby said body structure and said door member may be removedas a unit from said mounting structure to provide access to the interiorof the shell structure.

6. The structure recited in claim 4 in which said mounting structure isattached to an upwardly extending portion of the shell structure,

said wall portion has an upwardly extending deflector plate attachedthereto and partly defining said third opening,

said third opening facing upwardly whereby upon rupture of the seal torelieve the internal fluid pressure, the escaping fluid is deflected bysaid deflector plate and vented through said third opening in an upwarddirection.

References Cited by the Examiner UNITED STATES PATENTS 833,694 10/06Parker.

2,17%:686 11/39 Georgiev et al. 220--89 THERON E. CONDON, PrimaryExaminer.

FRANKLIN T. GARRETT, Examiner.

1. A BLOW-OUT DOOR STRUCTURE FOR PROTECTING A SHELL STRUCTURE AGAINSTDAMAGE DUE TO INTERNAL OVERPRESSURE, COMPRISING A BODY STRUCTURE HAVINGAN ENLARGED OPENING DEFINED BY A FLANGE PORTION, SAID FLANGE PORTIONHAVING A SUBSTANTIALLY CONTINUOUS FIRST PERIPHERAL FACE PORTION, A DOORMEMBER HAVING A SECOND PERIPHERAL FACE PORTION DISPOSED IN FACE-TO-FACERELATION WITH SAID FIRST FACE PORTION, A LAYER OF ADHESIVE MATERIALDISPOSED BETWEEN SAID FIRST AND SECOND FACE PORTIONS AND COEXTENSIVEPERIPHERALLY THEREWITH, SAID LAYER OF MATERIAL BONDING SAID DOOR MEMBERTO SAID BODY STRUCTURE AND PROVIDING A FLUID-TIGHT SEAL THEREBETWEEN ATTOTAL INTERNAL PRESSURES BELOW A PREDETERMINED VALUE, BUT BEINGYIELDABLE AT SUBSTANTIALLY SAID PREDETERMINED VALUE TO BREAK SAID SEALAND RELEASE SAID DOOR, AND MEANS FOR HOLDING SAID DOOR CAPTIVE IN SAIDBODY STRUCTURE.